It’s quite interesting moving away from the frame based game programming paradigm that traditional application might use to the object based system used by silverlight. In the traditional way where we would regenerate each game frame as required in the game loop, in silverilght we have to create persistent objects to represent the changing parts of the display – so for example the cell highlighting that occurs as you drag around a digit to the playing area traditionally would simply be drawn when the frame is rendered in the right place (with presumably an invalidation on mouse move) in silverlight we must actually create a persistent “rectangle” object that we change the coordinates of.